Search

Background: Cerebral amyloid angiopathy-related inflammation (CAA-ri) is a rare meningoencephalitis that presents with focal neurological deficits, cortical microbleeds and asymmetrical white matter lesions, usually steroid-responsive. It shares radiological features with amyloid related imaging abnormalities (ARIA), described in Alzheimer's disease (AD) patients that receive antiamyloid therapies, suggesting a common pathophysiological process. Methods: Clinical, neuropsychological and radiological description; APOE genotyping and cerebrospinal fluid (CSF) biomarkers (Aβ 42, Aβ 40, t-Tau, p-Tau and anti-A b autoantibodies) were determined in four patients with probable CAA-ri. PET imaging with Florbetapir was performed in two subjects, and one of them had a PET-PIB additionally. Patients received steroids and were clinically evaluated. T hree patients had imaging and CSF follow-up. Results: Mean age of presentation was 73.5 years (range 69-78), 50% were men. All patients presented with neurological focal symptoms and cognitive impairment. MRI showed cortical microbleeds and asymmetrical hyperintense white matter lesions. Allelic frequency for APOE-e4 was 62.5%. Aß40 and Aß42 levels were decreased and anti-Ab autoantibodies were high in all cases. A PET with Florbetapir, performed in two patients, and a PET-PIB performed in one of them, showed cortical amyloid deposits. After corticosteroid administration, a complete (1/4) or partial (3/4) resolution of focal symptoms was observed. One patient suffered an intracerebral lobar hemorrhage six months after the resolution of focal symptoms. On the follow-up MRI, a significant reduction of white matter lesions was appreciated. CSF anti-Ab autoantibodies at follow-up were markedly reduced in all cases. Conclusions: The pattern in CSF and amyloid PET biomarkers and the presence of APOE-e4 in CAA-ri suggests an important role of vascular amyloidosis. Anti-Ab autoantibodies may be a specific biomarker for this process, and could be useful for CAA-ri diagnosis and monitoring the response to treatment.

Canine venereal transmissible tumor (CTVT) is a round cell benign neoplasia that affects the external genital mucous which is transmitted during coitus with infected dogs. The normal canine behaviour such as smelling and sucking allow the tumoral cells to implant into extragenital zones with subsequent metastases formation. This report described a dog with multiple skin nodules localised in the thoracolumbar area and eyes. The nodules were ulcered and alopecic with purulent fluid around them. A granulomatous mass with focal necrosis area was also detected with bilateral keratitis. Citological analysis of skin nodules, eyelid tissue and granulomatous tissue on the base of the penis suggested a CTVT, and the histopathological analysis confirmed the diagnosis of CTVT. Also LINE-1 rearrangement in c-myc was detected as a genetic alteration of the CTVT. A chemotherapy protocol was started with vincristine sulfate. Haemograms were used previous to each chemotherapy sessions to prevent myelosuppression. A moderate non regenerative anemia was observed after the third session but it was resolved by discontinuing chemotherapy for two weeks. The chemotherapy was effective to eliminate the CTVT after six sessions. &nbsp, El tumor venéreo transmisible canino (TVT) es una neoplasia benigna de células redondas que afecta frecuentemente la mucosa genital externa de perros. El olfateo y el lamido permiten la implantación de las células tumorales en zonas extragenitales con formación de metástasis. Se relata un caso de TVT diseminado en piel, párpados y pene en un perro macho mestizo. Las lesiones localizadas en la parte dorsal y lateral de la zona torácica y abdominal presentaban varios nódulos alopécicos ulcerados y bien vascularizados, con aspecto friable y con secreción purulenta. El párpado superior izquierdo y derecho presentaban una masa granulosa con áreas de necrosis y queratitis bilateral. En la base del pene se presentaba una masa granulosa firme y bien delimitada. El análisis citológico de los nódulos cutáneos, de los párpados y la masa del pene reveló hallazgos compatibles con TVT, el que fue confirmado con análisis histopatológico. Además se determinó la presencia de LINE-1 en el oncogen c-myc como una alteración genética conocida para CTVT. Se estableció un protocolo quimioterápico sobre la base de sulfato de vincristina. Previo a cada sesión de quimioterapia se tomaron hemogramas para prevenir mielosupresión. Posterior a la tercera sesión se observó una anemia no regenerativa moderada que fue resuelta suspendiendo durante 2 semanas la terapia. La terapia con sulfato de vincristina fue efectiva para producir la regresión de todos los tumores en 6 sesiones, sin mostrar recurrencia. &nbsp

To assess metabolic changes in cerebral F-18-FDG PET/CT in premanifest and manifest Huntington's disease (HD) subjects compared to a control group and to correlate F-18-FDG uptake patterns with different disease stages. Thirty-three gene-expanded carriers (Eight males; mean age: 43 y/o; CAG > 39) were prospectively included. Based on the Unified Huntington's Disease Rating Scale Total Motor Score and the Total Functional Capacity, subjects were classified as premanifest (preHD = 15) and manifest (mHD = 18). Estimated time disease-onset was calculated using the Langbehn formula, which allowed classifying preHD as far-to (preHD-A) and close-to (PreHD-B) disease-onset. Eighteen properly matched participants were included as a control group (CG). All subjects underwent brain F-18-FDG PET/CT and MRI. F-18-FDG PET/CT were initially assessed by two nuclear medicine physicians identifying qualitative metabolic changes in the striatum. Quantitative analysis was performed using SPM8 with gray matter atrophy correction using the BPM toolbox. Visual analysis showed a marked striatal hypometabolism in mHD. A normal striatal distribution of F-18-FDG uptake was observed for most of the preHD subjects. Quantitative analysis showed a significant striatal hypometabolism in mHD subjects compared to CG (p < 0.001 uncorrected, k = 50 voxels). In both preHD groups we observed a significant striatal hypometabolism with respect to CG (p < 0.001 uncorrected, k = 50 voxels). In mHD subjects we observed a significant striatal hypometabolism with respect to both preHD groups (p < 0.001 uncorrected, k = 50 voxels). F-18-FDG PET/CT might be a helpful tool to identify patterns of glucose metabolism in the striatum across the stages of HD and might be relevant in assessing the clinical status of gene-expanded HD carriers due to the fact that dysfunctional glucose metabolism begins at early preHD stages of the disease. F-18-FDG PET/CT appears as a promising method to monitor the response to disease-modifying therapies even if applied in premanifest subjects.

Background: The APOE effect on Alzheimer Disease (AD) risk is stronger in women than in men but its mechanisms have not been established. We assessed the APOE-by-sex interaction on core CSF biomarkers, brain metabolism and structure in healthy elderly control individuals (HC). Methods: Cross-sectional study. HC from the Alzheimer's Disease Neuroimaging Initiative with available CSF (n = 274) and/or 3T-MRI (n = 168) and/or a FDGPET analyses (n = 328) were selected. CSF amyloid-ß1-42 (Aß1-42), total-tau (t-tau) and phospho-tau (p-tau181p) levels were measured by Luminex assays. We analyzed the APOE-by-sex interaction on the CSF biomarkers in an analysis of covariance (ANCOVA). FDG uptake was analyzed by SPM8 and cortical thickness (CTh) was measured by FreeSurfer. FDG and CTh difference maps were derived from interaction and group analyses. Results: APOE4 carriers had lower CSF Aß1-42 and higher CSF p-tau181p values than non-carriers, but there was no APOE-by-sex interaction on CSF biomarkers. The APOE-by-sex interaction on brain metabolism and brain structure was significant. Sex stratification showed that female APOE4 carriers presented widespread brain hypometabolism and cortical thinning compared to female non-carriers whereas male APOE4 carriers showed only a small cluster of hypometabolism and regions of cortical thickening compared to male non-carriers. Conclusions: The impact of APOE4 on brain metabolism and structure is modified by sex. Female APOE4 carriers show greater hypometabolism and atrophy than male carriers. This APOE-by-sex interaction should be considered in clinical trials in preclinical AD where APOE4 status is a selection criterion.

Summary This paper presents a new analytical solution to obtain the shut-in wellbore pressure at a vertical well that had been producing at a constant wellbore hole pressure from a closed-boundary reservoir with multiple wells producing at constant, different wellbore pressures. The analytical solution is a set of coupled simultaneous equations in the Laplace space (one for each well). These are obtained by using separation of variables, Green's functions, and the unit-step function with the methods of Rodriguez and Cinco-Ley1 and Camacho-V. et al.2 The equation for the shut-in well is nonlinear, preventing us from obtaining the formal solution of the set of equations either in real time or in Laplace space. A number of approaches were used to make the solution tractable. These included expansion of Green's function for large times, a Taylor series expansion of the rates around the time of shut-in, and application of the concepts of Najurieta.3 None of the approaches gave satisfactory results.

The purpose of this paper is to document transient behavior at a well that produces a fractured reservoir by solution-gas drive. The authors consider the dual-porosity model Barenblatt et al. and Warren and Root introduced and the dual-permeability model Bourdet presented. These idealizations are considered to demonstrate the consequences of production from the matrix system. They document pressure and saturation behaviors in the fracture and matrix systems. The interaction between the matrix and the fracture systems under multiphase flow conditions also is discussed. For convenience, they refer to the Warren and Root model as the dual-porosity model and to the Bourdet idealization as the dual-permeability model.

This paper analyzes the influence of gravity segregation effects on inflow performance relationship (IPR) curves, with both totally and partially penetrated vertical wells. Using synthetic responses from a finite difference simulator, the effects of different parameters, such as vertical to radial permeability ratio, production mode, position of productive interval, oil rate, and mechanical skin, on the shape of IPR curves are documented. It is shown that greater flow potentials are obtained when the ratio of gravity to viscous forces increases. It is shown that for the case of partially penetrated wells, the IPR curve generated at constant bottomhole pressure does not coincide with the IPR generated at constant oil rate. Also, the presence of gravity segregation affects the values of absolute open flow potential, obtaining big differences with the corresponding values when gravitational effects are ignored. The values of the exponent n of Fetkovich IPR and the coefficients of the quadratic equation proposed by Jones et al. are functions not only of time but also of production rate, position of productive interval, and other parameters. The consequence of the above results is that the interpretation of IPR curves is affected by the presence of gravitational effects and therefore the use of traditional methods, such as those of Vogel , Fetkovich, or Jones et al., is restricted to the specific conditions considered by these authors.

Summary This paper presents results pertinent to the analysis of well performance in solution-gas-drive systems. The characteristics of wells producing solution-gas-drive systems are documented. Procedures to correlate multiphase flow solutions with single-phase flow systems for both transient and boundary-dominated flows are presented.

Summary This paper presents procedures to obtain reservoir parameters from constant-pressure drawdown data in solution-gas-drive reservoirs. A novel procedure to determine the mechanical skin factor is introduced. Examples, including a field case, illustrate the use of this procedure. An estimate of the drainage area can be obtained with the derivative of rate data. A theoretical basis for analyzing data by the pressure-squared, p2, approach is presented; this procedure permits the approximate determination of sandface effective permeabilities in the transient flow period. For damaged wells, it is possible to obtain rough estimates of the size of the skin zone and the ratio of reservoir/skin-zone permeability when early transient data are available. The expression of the appropriate dimensionless rate in terms of physical properties for solution-gas-drive systems is presented. Finally, this paper presents a procedure to obtain an estimate of the change in sandface saturation during the transient flow period.

La Laguna Hule, localizada en la Vertiente Caribe, Costa Rica a 750m sobre el nivel del mar, forma parte del complejo de lagunas volcánicas llamado “Bosque Alegre”. El área de la laguna es de 60.3 ha y su profundidad máxima de 22.5m. La investigación se realizó de abril a setiembre de 1989 determinándose, en cada muestreo la temperatura, el óxido disuelto, el ácido sulfhídrico (H2S), el pH, la alcalinidad y la concentración de iones calcio, magnesio, hierro y manganeso.La laguna presenta un perfil clinógrado de oxígeno; el 60% del volumen total es anóxico con presencia de H2S a partir de los 8m de profundidad. Los valores de pH y alcalinidad indican que las aguas son bicarbonatadas, caracterizándose por un alto contenido de hierro. La curva de temperatura señala una diferencia de hasta 4.3 °C entre la superifcie y el fondo, permitiendo a la laguna permanecer estratificada (hay un epilimnion y un hipolimnion bien definido). The “Laguna Hule” a medium size volcanic lake, is located at 750m above sea level on the Caribbean side of the Cordillera Volcánica Central in Costa Rica. Hule is one of three in a lake complex known as “Bosque Alegre”. The lake area is 60.3 ha and its maximum depth reaches 22.5 m.Some selected physical and chemical features were measured and discussed here. Dissolved oxygen exhibits a clinograde profile, with 60% of the water volume being anoxic and containing hydrogen sulphide H2S below 8m depth. The temperature profile shows a maximum difference of 4.2 °C showing stratification during the study period. The lake is of the bicarbonate type with a high concentration of Fe+2 in the hypolimnion.

This work examines the well and reservoir performance under both solution gas-drive and gravity drainage in homogeneous systems. Based on synthetic information obtained with a fully implicit black-oil simulator, the influence of different parameters like oil rate, position of the producing interval, wellbore pressure level, skin factor, and vertical permeability, for both constant oil rate and constant pressure production modes are documented. Analytical results for the reservoir performance during the boundary dominated flow period are derived. An approximate expression that describes the variation of oil saturation with average pressure is presented. For constant oil rate production, the influence of gravity drainage on the inflow performance relationships curves is studied, and a new correlation is presented. For constant pressure production, the decline curve behavior is analyzed and it is found that under favourable gravitational effects, the production behavior shows two decline stages such as double porosity systems; however, it does not follows the typical decline type curves for naturally fractured reservoirs. At certain backpressure values during the first stage an exponential decline behavior could be observed, while during the second stage values of the decline exponent less than zero are observed.

This work presents results on the optimization of production systems performance for oil and gas reservoirs. Genetic and Polytope algorithms are used for the nonlinear optimization problem considering appropriate values of several variables like tubing string and wellhead choke diameters, separator pressure and surface pipeline diameter. The model considers several components and different methods to evaluate the pressure drop in each component. The sensitivity of each component of the system can be evaluated. This model includes a mechanistic model to predict the pressure drop due to multiphase flow for any tubing angle with upward and downward flow. The method of splines is used to eliminate the presence of pressure gradient discontinuities in flow pattern boundaries. This property of the model allows us to use optimization algorithms in an efficient manner. Several examples are presented to illustrate the methodology proposed in this work.

El objetivo de este estudio es establecer diferentes modelos matemáticos para dar una aproximación de los rendimientos obtenidos en las explotaciones de eucalipto de la provincia de Huelva. Estos rendimientos han sido relacionados con distintas variables propias del monte y de la organización de los trabajos. Las variables estudiadas han sido: la pendiente, la distancia de desembosque y la densidad de masa. Asimismo, las operaciones consideradas fueron básicamente el procesado de la madera y el desembosque., This research work aims to stablish some mathematical models, in order to give an estimation to clearcutting efficiency in Eucalyptus stands in the province of Huelva. These working yields have been related to different forest variables, as well as the types of working setups. The variables analyzed have been: slope, logging distance and felling density. The operations taken in account were basically trunk processing and logging.

Abstract The effect of capillary pressure on well test is investigated. Solution gas-drive, homogeneous and naturally fractured reservoirs are considered. A numerical simulator, with a Warren and Root formulation for the case of fractured reservoirs, is used to generate synthetic data. For homogeneous reservoirs the procedures of Perrine-Martin and pseudo-pressure are evaluated under the presence of capillary pressure. As expected the influence of capillary pressure is more pronounced in buildup tests than in drawdown tests. A capillary pressure number is proposed to evaluate the importance of capillary forces over viscous forces in different regions in the reservoir. For naturally fractured reservoirs, the effects of including capillary pressure in the fracture and matrix systems are investigated. It is observed that, under certain conditions, both drawdown and buildup tests show capillary pressure effects in different flow periods under transient conditions. Also, the influence of capillary pressure on the flow transfer between matrix and fracture is documented, observing that the oil flow rate per unit volume from the matrix to the fracture system is lower when capillary pressure is taken into account. P. 421

A computer program has been developed for simulating two-phase flow in horizontal and inclined pipes. This program is based on the mechanistic model of Xiao et al., extending the inclination angle from ± 15° to the range: ± 45°, using the works of Barnea and Hasan and Kabir. With this hybrid model it is determined the flow pattern, under stationary conditions, and hydrodynamic characteristics of the flow pattern, mainly hold-up and pressure gradients. An analysis of synthetic information, generated with the computer program, has been done. Based on statistical parameters, the mechanistic model performance has been compared with that of Beggs and Brill correlation, observing similar trends, with both procedures for the whole range of pipe inclination angles. Finally, through 3-D graphs, performance of principal hydrodynamic parameters has been presented. Mechanistic models for multiphase flow in pipes consider the basic physical phenomena for their development. The inclination angle is one of the main parameters that control flow characteristics. One of these models is that of Xiao et al., developed for horizontal and close to horizontal pipes.

This paper was prepared for presentation at the 1998 SPE International Petroleum Conference and Exhibition held in Villahermosa, Mexico, 3-5 March 1998.

Introducción La biodiversidad se ha constituido en los últimos años en uno de los puntos centrales de la agenda de las conferencias internacionales con la agricultura, la biotecnología y las negociaciones comerciales entre gobiernos y empresas. Antes de la mitad de la década de los ochenta, la biodiversidad no era considerada tan relevante como actualmente. Las consecuencias más serias derivadas de la Revolución Verde ha puesto en evidencia la fragilidad de la base genética en al que se sustenta la agricultura moderna y las ganancias económicas que de ella se pueden obtener…